Ferrous alloys



Patented Mar. 11, 1952 FERROUS ALLOYS James P. Gill, Latrobe, Pa.,assignor to Vanadium-Alloys Steel Company, Latrobe, Pa.,-a corporationof Pennsylvania No Drawing. Application August 5, 1950, Serial No.177,963

7 Claims.

This invention relates to a new and unusual alloy steel suitable fortools and dies and to a method of controlling the physicalcharacteristics of hardness and toughness in the steel.

It is recognized that tools and dies which are subject to abrasiveWearing at the surface and heavy shock must have a hard, wear-resistantsurface backed up by a strong, tough core. Numerous attempts have beenmade to provide tool steels having these properties, but to my knowledgenone has been successful. It is possible to make a steel which will havean intensely hard surface, but all of the prior art steels which havebeen so prepared have either become hardened to a depth which affectsthe strength and toughness of the core or the hard exterior layer is sothin that it will crack or shatter under pressure or shock.

It is an object of the present invention to provide an alloy steel whichis capable of resisting both shock and surface wear.

Another object of the invention is to provide a method of controllingthe thickness of the wear-resistant surface layer of an alloy steel.

In its broadest sense, the invention contemplates the addition of acombination of alloying metals to a. high-carbon, high-tungsten steel inan amount sufficient to result in hardening an exterior surface layerwithout hardening or affecting the strength of the core.

High-carbon, high-tungsten steels were among the earliest alloy toolsteels. Steels containing high percentages of carbon and tungsten alongwith small percentages of other metals such as manganese were known tohave a hard surface but it was determined that this hardness extendedthroughout the cross sectional dimension of the steel bar. These hard,brittle steels were adequate for certain purposes, such as for tools,lathes, planers and the like, which were designed for heavy cuts whereinshock resistance was not an important feature. These brittle steels werenot satisfactory for use in tools and dies which were subject to impact,pressure or shock.

I have now discovered an alloy tool steel having certain definiteconcentrations of alloying elements as will be set forth in detailhereinafter. These steels will have a tough shock resistant core and a,hard wear-resistant surface layer which is not subject to chipping orshattering. I have also discovered that I can vary the thickness of thehardened exterior layer by varying the amount of alloying elements inthe steel.

The following examples illustrate the various steels which I haveprepared in the practice of the present invention along with anexplanation of the best reasons available to me for the action of thevarious steels. It should be understood that I do not wish to be limitedto any particular theory since the art of alloy steels is extremelycomplex and open to controversy. In each of the following examples theconcentrations are given in percentages by weight unless otherwisespecified.

Example I A steel was prepared by melting together iron suitable for usein tool steels along with the folv lowing alloying elements:

Per cent Silicon .25 Manganese .30 Chromium .38 Carbon 1.91

Tungsten 10.19

and traces of impurities. Samples 1 in diameter and 4" long of this heatwere quenched at 1600 F. The samples were found to have an tensely hardsurface layer which penetrated approximately 7 of an inch. Such ahardness penetration is desirable in a steel which must have exceptionalresistance to Wear and, at the same time, withstand heavy shock and highpressures.

Example II A heat was prepared by melting a suitable iron along with thefollowing alloying elements:

this steel were quenched as in Example I and were found to have acomparable hardness penetration. The element vanadium did not materiallychange. the hardening characteristics of the composition.

It was found that molybdenum could be sub stituted for the silicon,manganese orchromium in either Example I or Example II Withoutmaterially afiecting the hardening characteristics of the samples.

Example III A high carbon, high tungsten heat was prepared using asuitable iron and alloying elements in the following proportions:

Per cent Silicon .27 Manganese .27 Carbon 1.65 to 2.50 Tungsten 7.50 to15.00

When samples of this steel were quenched and tested, they were found tohave a hard layer that was very thin, i. e., /64 to /a4 of an inch. Sucha thin hardened surface layer will not withstand heavy shock orpressure.

Example IV A heat was prepared employing suitable iron and alloyingelements in the following proportions:

Per cent Silicon .34 Manganese 1.48 Carbon 2.19 Tungsten 10.37

' When samples of this steel were quenched and tested, they were foundto be extremely hard, but the hardness extended all the way through the1 samples. Such a steel is typical of the older type tool steels whichare unsuitable for use where they are subjected to shock and pressure.

Other heats and tests were made which have led me to conclude that thenovel and unusual properties of my tool steel can be achieved only bycarefully following the method outlined herein and limiting the amountsof alloying elements as will be hereinafter. described.

cording to Example IV was 64 on the Rockwell C scale and a centerhardness of 61 on the scale. It will be seen that this steel wasapproximately the same hardness all the way through and did not have atough core. The steel made according to Example III had the same hardsurface and soft core as the steels made according to Examples I and IIbut the hard layer was very thin and penetrated an insufficient depth ofabout /64 to /64 of an inch.

This application is a continuation in part of my copending applicationSerial No. 750,887, filed May 27, 1947, now abandoned, which was acontinuation in part of my then copending application Serial No.659,878, filed April 5, 1946, now abandoned.

The invention is hereby claimed as follows:

1. An improved forgeable and machinable quenched "alloy steel consistingessentially of In general it maybestatedthatmy new alloy steel is animproved forgeable and machinable alloy steelcontainingironand the usualimpurities'and from 1.65% vto 2.50.% carbon, from 7.50% to 15.00%tungsten, from 0 to 2.50% vanadium and not more than 1.50% ofa'combination of at least three alloying elements from the groupconsisting of silicon, manganese, chromium and molybdenum and thebalance iron and the normal impurities of sulfur and phosphorus. Thesilicon, manganese, chromium and molybdenum may be individually presentin amounts between .10% and 1.00%. A steel prepared according tothe-formula outlined above will be found to have a" tough, ductile,shockresistantcore and 'a hard, wear-resistant surface layer which willbe at least /64 of an inch in thickness and may be of a greaterthickness which will not affect the toughness and softness of. the core.

'The thickness of the hardened surface layer can be adjusted andcontrolled by adjusting the amount of alloying elements which are addedto the steel. For example, if the amount of silicon, chromium, manganeseand molybdenum is maintained below 1.00% (as in Example I) a certainthickness is achieved. If the amount is increased nearly to 1.50%, thehardened surface layer will be thicker.

In order to illustrate the physical characteristics of a steel preparedaccording to the invention,-but without intending to limit the inventionin any way, it may be stated that the hardness of'the surface layer isapproximately 6&1 to 68 on the'Rockwell C scale. The hardness of thecore of the specimens prepared according to Examples I and II wasapproximately 47 on the Rockwell C scale. On the other hand, the surfacehardnessof the samples prepared ac about 1.65% to about 2.50% carbon,about 7.50% to about 15.00% tungsten, from 0% to 2.50%

vanadium, an amount not exceeding 1.50% of a combination of at leastthree alloying elements from the group consisting of silicon, manganese,chromium and molybdenum and the balance iron and the normal impuritiesof sulfur and phosphorus, said alloying elements being individuallypresent in amounts between 0.10% and 1.00%. 2. An improved forgeable andmachinable quenched alloy steel consisting essentially of about 1.65% toabout 2.50% carbon, about 7.50%

to about 15.00% tungsten, from 0% to 2.50%

vanadium and an amount not exceeding 1.50%.

of a combination of at least three alloying elements from the groupconsisting of silicon, man- 'ganese, chromium and molybdenum and thebalance iron and the normal impurities of 'sulfur' and phosphorus, saidalloying elements being individually present in amounts between 0.10%

bar 1 /2 inches in diameter or larger.

3. An improved forgeable and machinable quenched alloy steel consistingessentially of about 1.65% to about 2.50% carbon, about 7.50% to about15.00% tungsten, from 0% to 2.50% vanadium, about 0.25% silicon, about0.30% manganese and about 0.38% chromium and the balance iron and thenormal impurities of sulfur and phosphorus.

4. -A method of making an improved forgeable and machinable alloy steelwhich comprises melting together about 1.65% to about 2.50% carbon,about 7.50% to about 15.00% tungsten, from 0% to 2.50% vanadium, anamount not exceeding 1.50% of a combination of at least three alloyingelements from the group consisting of silicon, manganese, chromium andmolybdenum and the balance iron and the normal impurities of sulfur andphosphorus, said alloying elements being individually present in amountsbetween 0.10% and 1.00% and quenching said steel.

5. A method of making an improved forgeable and machinable alloy steelwhich comprises melting together about 1.65% to about 2.50% carbon,about 7.50% to about 15.00% tungsten, from,

0% to 2.50% vanadium, an amount not exceeding 1.50% of a combination ofat least three al-' loying elements from the group consisting ofsilicon, manganese, chromium and molybdenum: and the balance iron andthe normal impuritiesof sulfur and phosphorus, said alloying elementsbeing individually present in amounts between 010%. and 1.00% andheating and quenching said,

steel, said amount being effective to cause hardening from the surfaceto about 4 of an inch across the section of a round bar about 1 inchesin diameter or larger.

6. A method of adjusting and controlling the thickness of a hardenedsurface layer in an alloy steel having a carbon content of about 1.65%to about 2.50% and a tungsten content of about 7.50% to about 15.00%,which comprises essentially incorporating into said steel while molten10 an amount not exceeding 1.50% by weight of a combination of at leastthree alloying elements from the group consisting of silicon, manganese,chromium and molybdenum, said alloying elements being individuallypresent in amounts between 0.10% and 1.00% and quenching said steel.

7. A method of adjusting and controlling the thickness of a hardenedsurface layer in an alloy steel having a carbon content of about 1.65%to about 2.50% and a tungsten content of about 7.50% to about 15.00%,which comprises essentially incorporating into said steel while moltenabout 025% silicon, about 0.30% manganese and about 0.38% chromium andquenching said steel.

JAMES P. GILL.

REFERENCES CITED The following references are of record in the file ofthis patent:

Alloys of Iron and Tungsten, pages 159 to 160. Edited by Gregg.Published in 1934 by the Mc- Graw-Hill Book 00., New York, N. Y.

2. AN IMPROVED FORGEABLE AND MACHINABLE QUENCHED ALLOY STEEL CONSISTINGESSENTIALLY OF ABOUT 1.65% TO ABOUT 2.50% CARBON, ABOUT 7.50% TO ABOUT15.00% TUNGSTEN, FROM 0% TO 2.5% VANADIUM AND AN AMOUNT NOT EXCEEDING1.50% OF A COMBINATION OF AT LEAST THREE ALLOYING ELEMENTS FROM THEGROUP CONSISTING OF SILICON, MANGANESE, CHROMIUM AND MOLYBDENUM AND THEBALANCE IRON AND THE NORMAL IMPURITIES OF SULFUR AND PHOSPHORUS, SAIDALLOYING ELEMENTS BEING INDIVIDUALLY PRESENT IN AMOUNTS BETWEEN 0.10%AND 1.00%, SAID AMOUNT BEING ADJUSTED TO CAUSE HARDENING FROM THESURFACE TO A DEPTH OF ABOUT 7/64THS OF AN INCH ACROSS THE SECTION OF AROUND BAR 1 1/2 INCHES IN DIAMETER OR LARGER.